Urgency urinary incontinence (UUI) is involuntary leakage accompanied by or immediately preceded by urgency. While UUI appears to involve the neural pathways that control micturition, the etiology is incompletely understood. On the basis of our groundbreaking findings that clearly show that female human bladders are not sterile despite negative urine culture status, we propose the novel hypothesis that bacterial colonization of the lower urinary tract influences UUI symptoms and outline experiments to test this hypothesis. If our findings support our hypothesis, we will have provided novel insights into UUI etiology. If bacterial community structure correlates with UUI, then treatments could be targeted to modify this bacterial community. Such studies would have immediate clinical impacts and would be well suited for NIH- sponsored clinical trials networks.